A wire harness to be arranged in a vehicle such as an automobile includes an electric wire and an electric wire protection member for protecting the electric wire. In some cases, a high-voltage electric wire such as an electric wire for connecting a battery and an engine is inserted into the electric wire protection member, for example.
This type of electric wire protection member includes a metal pipe. The surface of the electric wire protection member is colored a certain color such that the insertion of the high-voltage electric wire can be visually confirmed during the arrangement of the wire harness, the removal of the wire harness, and the like. For example, Patent Documents 1 (JP2014-50267A) and 2 (JP2014-50268A) disclose a technique of forming an identification mark on a portion of the outer surface of the metal pipe body, using a coloring agent such as paint or tape.
A metal pipe to be used in the electric wire protection member is produced through molding such as extrusion molding. Right after the molding, processing oil used during the molding adheres to the surface of the metal pipe. When an attempt is made to form the identification mark while this processing oil remains, there is a risk that the adhesion of the identification mark will decrease due to the processing oil existing between the identification mark and the metal pipe. In general, in order to prevent such problems, the identification mark is formed after the metal pipe is degreased and the processing oil is thus removed from the surface of the metal pipe. Also, in general, in order to improve the adhesion of the identification mark, a primer coat is applied between the identification mark and the metal pipe.
In addition, a technique of forming an identification mark using a material having oily-surface adhesion, such as the photo-curable material disclosed in Patent Document 3 (JP2014-159522A), has also been considered.